1. Field of the Invention
The present invention relates to a stylus pen (input device) which is used to input information into information processing equipment, such as a computer.
2. Description of Related Art
A conventional stylus pen, which is used as an input device of a computer, typically displays positional data (i.e., two-dimensional data in a cartesian coordinate system) on an input and output display (i.e., board or panel) and is merely an input device auxiliary to the keyboard. A stylus pen is known which has a switch that is turned ON and OFF in response to mechanical displacement of a nib (i.e., writing tip) or pressure applied to the nib. Such a device is used, for example, to indicate selection of letters, FIGURES, or symbols on a display screen, input necessary operations, input positional data of a coordinate system on the display screen, draw freehand FIGURES or letters, or identify the same, etc. The- pressure applied to the tip of the stylus pen is detected by a pressure sensor which actuates the switch when the detected pressure is above or below a predetermined threshold value.
In recent computers which do not use a keyboard as an input means, it is necessary to provide the stylus pen with a 3-dimensional input function (i.e., an input function using Z-directional data of a cartesian coordinate system in addition to X-Y coordinate data). In such a known stylus pen having an X-Y-Z coordinate data inputting function, color density data is input and the size of a selected FIGURES or letter is changed in accordance with the pressure (i.e., mechanical force) applied to the tip.
In conventional stylus pens which can detect mechanical force, detection is in principle effected in accordance with an output, such as resistance, electrostatic capacity, or magnetic field, which varies depending on the stroke (i.e., linear reciprocating movement) of the tip of the pen. Therefore, in order to increase the output, it is necessary to increase the stroke of the tip. However, it is difficult for a user to use a stylus pen having a large stroke.
Furthermore, the known type of stylus pen in which a mechanical displacement of the tip is directly applied to a diaphragm of the pressure sensor, as mentioned above, does not have a large resistance to shock or overload. Consequently, for instance, if the pen is accidentally dropped, inducing shock to the pen tip, the pen can be easily broken. In practice, during the course of usage of the stylus pen, for example, with a personal computer, the stylus pen is often dropped, etc., jamming the tip of the pen. Accordingly, to increase the life of the pen, it is necessary to provide a stylus pen tip that is capable of withstanding a large degree of external shock.